If you are a prospective or current college student who will be studying in the science and/or medical programs your school offers, you are most likely going to be required to purchase a lab coat.
Some Classes Which Require Lab Coats
Any science class that requires you to be in a laboratory as part of the course will generally also require you to wear a lab coat during any lab work. Biology, biochemistry, chemistry, microbiology, and physics are all classes that will likely require a lab coat, and there are other science classes which will require one as well.
Obtaining a Lab Coat
If you are attending a college or university that specializes in science and/or medical programs, you can probably purchase lab coats in the college bookstore. If they are not available on the shelf at the college bookstore, sometimes the college will order lab coats for you if you ask the person in charge at the bookstore.
Another way to obtain a lab coat for your science lab classes would be to get in contact with the students who have taken the class prior to this semester. If a previous student no longer needs his or her lab coat, you may be able to pick one up pretty inexpensively.